Small-scale Experimental Testing of a Novel Marine Floating Platform with Integrated Hydro-pneumatic Energy Storage

•More than 93% of the energy stored by liquid-piston compression can be recovered.•Time that stored energy is held in the system has little effect on cycle performance.•60% increase in pre-charge pressure did not cause noticeable change in performance.•Meteorology plays a significant role: colder seasons slightly reduce capacity.•Storm data shows rapid response of internal air to sudden external temperature drop.